The present invention relates to a new and improved method of, and apparatus for, continuously texturing or crimping thermoplastic filaments.
In its more particular aspects, the texturing or texturizing method of the present invention is of the type wherein thermoplastic filaments are blown-in or introduced in the form of a filament bundle by means of a jet or stream of a heated medium with the aid of a jet nozzle into a stuffing chamber of elongate curvature or curved configuration substantially tangentially with respect to such elongate curvature of the stuffing chamber and at a forwarding speed which is greater than the circumferential velocity of the stuffing chamber.
As to the texturing or texturizing apparatus of the present development such is of the type which comprises a jet nozzle for introducing or blowing-in a filament bundle by means of a jet or stream of a medium, such as air, steam or mixtures thereof, into an annular or ring-shaped rotatable and drivable stuffing chamber. This stuffing chamber possesses an inlet or blow-in or receiving zone or region for receiving and crimping the filament bundle, a treatment or heat transfer zone or region for heating or cooling the received filaments of the filament bundle and a delivery zone or region for delivering or outfeeding the crimped filaments to a subsequent conveying element or fiber bundle-fitting or take-off element or means, for example, a cooling drum or drafting roller or conveying roller.
The main criteria as concerns crimping thermoplastic filaments, also sometimes referred to in the art as filament threads or yarns, are intense filament crimping in the crimping technique apparatus and durability of the filament crimping following the crimping operation. As to such type of filament crimping technique such constitutes a stuffing crimping operation wherein a filament bundle, which has been heated by a heated gaseous medium, is blown into a stuffing chamber where the stuffed filament bundle is brought into a crimped condition within the stuffing chamber because of the decelerated speed of conveyance of the filament bundle within the stuffing chamber. In this crimped condition the filament cools below the softening point so that when the crimped filament bundle is again withdrawn there remains a permanent crimp.
Such type of method is known, for example, from German Published Application No. 2,110,670, published Jan. 27, 1972. Here a jet nozzle blows-in or introduces the filament substantially tangentially into an elongate curved tunnel-like stuffing chamber. This stuffing chamber is provided in the circumferential or peripheral direction with a cooling drum which has a perforated surface. Cooling air is ejected through such perforated surface so that, as previously mentioned, the stuffed filament is cooled to produce thereat a permanent crimp.
This problem of fabricating a crimped filament is solved in a somewhat different manner in the apparatus which has been disclosed in German Published Patent Application No. 2,507,752, published Aug. 26, 1976. Here the filament thread which has been heated and pre-drafted by heated godets and after issuing from a jet nozzle is hurled against a screen wall in order to experience pre-crimping. The filament thread rebounding from the screen wall is then engaged by needles of a rotating belt so that the pre-crimped filament thread forms a plug between the needles. These needles then convey the plug into a heating channel or passage which narrows in order to compress the plug. Following the heating channel or passage the plug is then again released by means of a release device.
U.S. Pat. No. 3,816,887, granted June 18, 1974 discloses another construction of bulking or crimping apparatus wherein the filaments are blown-in or introduced in the form of a filament bundle or bunch by means of a stream of a heated medium and with the assistance of a jet nozzle into an elongate curved stuffing chamber substantially tangentially with respect to the curvature thereof and at a velocity greater than the circumferential velocity of the stuffing chamber. The injected filament bundle thus has imparted thereto a crimp which is subsequently cooled at the peripheral region of the stuffing chamber. The stuffing chamber comprises a groove formed in a cooling drum, and this groove is covered near to the site of blowing-in the filaments so that there is formed a closed chamber. Also, the base or floor of the groove is perforated so that external air can be sucked-in to cool the filaments. The crimped filaments are delivered at a predetermined location of the periphery of the groove to a subsequently arranged conveyor element.
One important aim or objective of a method or apparatus for continuously crimping thermoplastic yarns or threads is that the complete operation must not only give a result which is satisfactory from the technical point of view but it must also be very economical--i.e., operating conditions must be satisfactory and performance must be high. Operating conditions improve as less auxiliary agents, such as air, are required for cooling, or also improve in relation to the simplicity of construction of the crimping apparatus in order to achieve the same technological result with high efficiency, the term "technological result" denoting crimp density and durability or retentiveness of the crimp in the filament bundle during subsequent process steps.
A disadvantage of the heretofore discussed prior art is that most of the compounds or parts bounding the actual stuffing chamber are stationary and therefore very dependent on friction or frictional effects.